In a conventionally known coating booth of such a kind, an air supply chamber mounted at the ceiling of the booth has a double-layer structure in which a dynamic pressure chamber and a static pressure chamber are stacked one on top of the other. In the coating booth, air from an air supply duct is supplied laterally to the dynamic pressure chamber, and the air in the dynamic pressure chamber is allowed to flow down to enter the static pressure chamber via a flow-straightening plate, so that the air becomes less prone to become turbulent (for example, see Patent Literature 1).